Known display types mainly include liquid crystal displays and organic light emitting diode (OLED) displays. Liquid crystal displays have advantages such as having a thin body, reduced power consumption, low radiation, etc, as well as being widely used. Most of the liquid crystal displays on the market are backlight type liquid crystal displays. Each backlight type liquid crystal display includes a liquid crystal panel and a backlight module. Working principle of the liquid crystal panel disposes liquid crystal molecules between two parallel glass substrates, applying a driving voltage between the glass substrates to control rotational direction of the liquid crystal molecules, and then generating a picture by light transmitted from the backlight module.
Thin film transistor liquid crystal displays (TFT-LCD) have been rapidly developed and widely used in recent years due to their advantages, such as low power consumption, excellent picture quality, and high production yield. Specifically, the TFT-LCD is a layer of liquid crystals sandwiched between the two glass substrates, with a color filter disposed on the upper glass substrate, and thin film transistors disposed on the lower glass substrate. An electric field variation is generated when the current passes through the thin film transistor, a deflection of the liquid crystal molecules is caused by the electric field variation, and thereby polarity of the light is changed to achieve a desired display picture.
OLED display technology is different from traditional LCD display technology. For example, OLEDs do not require a backlight source, a very thin organic material coating is applied to the OLED, and the organic material coating is self-illuminating when current passes through it. The OLEDs have advantages such as having a high contrast, a wide color gamut, flexibility, a thin, light body, reduced energy consumption, etc, in recent years, the OLED display technology has gradually become widely used in the field of mobile devices, such as smart phones and tablet computers, the field of flexible wearable devices such as smart watches, the field of the large size curved-televisions (TV), and the field of white lighting. Momentum of the development of OLEDs is strong.
For OLED displays, some of the known OLED devices are produced by a vacuum deposition technology via a vapor deposition apparatus, others are produced by an ink-jet printing technology. For the OLED devices produced by the ink-jet printing technology, the prior art is shown as FIG. 1 and FIG. 2. FIG. 1 shows a pixel structure formed by the ink-jet printing technology in the prior art. FIG. 2 shows a pixel region structure as shown in the FIG. 1. The pixel structure 1 comprises a plurality of pixel units 2 and a plurality of pixel regions 4. Each of pixel regions 4 comprises a plurality of sub-pixel regions 5. The pixel units 2 are formed in the sub-pixel regions 5 by the ink-jet printing technology. Each pixel unit 2 comprises a plurality of sub-pixels 3 such as red pixels, green pixels, and blue pixels. Each of sub-pixels is formed in each of the sub-pixel regions.
In actual production process, the pixel region or the sub-pixel region is specifically formed by disposing a layer of a substrate on a light emitting region, and then providing a plurality of slots spaced from each other on the substrate, so as to form the sub-pixel regions. Next, a nozzle of an ink-jet printer is arranged toward the slots, which drops pixel material into each of the sub-pixel regions. Since a space in each slot of each sub-pixel region is small, the nozzle is not easily aligned with the sub-pixel regions. The pixel materials may easily drop in other positions out of the sub-pixel regions. In addition, since the space in each slot of each sub-pixel region is small, the pixel material in the slots easily overflow when a few drops of pixel material are dropped from the nozzle. It causes each of the pixel units to have an uneven thickness, and mura (spots) easily appear.